The invention relates generally to a control system, and more particularly to a control system and method for monitoring an integrated system and predicting events leading to an expected state of the integrated system.
Soaring fuel prices and shrinking water resources together with emerging global norms for conservation of water and energy are forcing industries to manage their power and water utilization more efficiently. Thus, industries are identifying ways to attain a significant reduction in fossil-fuel based power consumption and fresh water intake. One promising technology that enables significant reduction in power consumption and fresh water intake includes an integrated system having a water purification unit and a power generation unit. The power generation unit utilizes waste from the water purification unit to generate electrical power, and the integrated system operates on the electrical power generated by the power generation unit. Moreover, after meeting the power requirements of the integrated system, excess power is used for some other application. An example of the integrated system is General Electric waste-to-value system that generates electricity and process steam (heat) in a flexible manner while recovering potable high-quality water.
Typically, key units or components of a water purification system include a digester and a membrane bioreactor, while a key unit of a power generation system is a reciprocating gas engine or the like. The water purification system releases biogas as a waste that is consumed by the reciprocating gas engine to generate electrical power. Further, the key units of the water purification system operate in a coordinated and an interdependent fashion, hence any upsets or variations in any key unit affect functionality and performance of the rest of the key units. The wastewater feed stream to the digester, for example, may have significant variations in flowrates, influent chemical oxygen demand, total suspended solids, total dissolved solids, temperature, nitrogen, phosphorous, sulphates and pH. The variations in the digester, in turn, impact operation of downstream process units, such as the membrane bioreactor. Moreover, performance variations in the water purification unit may result in significant variations in flowrate, composition and heating value of the biogas resulting in tripping of the gas engine, ultimately resulting in upset and shutdown of the integrated system.
Conventionally, the variations in the key units are monitored by laboratory tests. Unfortunately, these lab tests are time consuming and are not sufficient for stopping frequent upsets of the integrated system leading to large dead time enclosed loop responses. Also, the operator of the integrated system is unable to detect any anomalous behavior of the integrated system until it is too late, thereby causing costly shutdowns and maintenance. Thus, due to absence of a realtime or near realtime monitoring process, the significant variations in the input feed cannot be monitored leading to expensive shutdowns of the integrated system.
It is therefore desirable to achieve robust and stable operation of the overall integrated system over long continuous periods of operation in the presence of wide-ranging variations. Further, it is desirable to have a realtime monitoring and control system configured to predict significant variations and disturbances in the integrated system well in advance, and take subsequent corrective actions to prevent the integrated system from stress leading to shutdowns.